.45 Auto Rim:What Load ?

Sea Buck · April 1, 2011, 11:05 AM

Looking in my Sierra Handgun Loading Manual I see a loads on the low end of the velocity scale that when compared to .45ACP in the same manual these loads are in the Max velocity area. For instance 6.4 gr of Unique in Auto rim for a 230 gr FMJ is listed as 700fps, the same load in .45 ACP gives 850 fps. For Bullseye in AR it's 4.9 gr / 750fps, and in ACP 4.9gr it's 850 fps. I don't understand this.Why does the same load in ACP give a higher velocity,it's the same case. I really don't want to shoot my 93 year old S&W at service load pressures. What do I use?

zippy13 · April 1, 2011, 11:23 AM

Are the test guns/barrels the same?
One thinks of .45 ACPs being used in 1911s and .45 Auto Rims in revolvers.
I shoot 3.5 gr Bullseye under a 200-gr LSWC in my 1917.

Sea Buck · April 1, 2011, 01:05 PM

Zippy, I use 4.5 gr Bullseye under 230 gr FMJand 4.0 Bullseye under a 230gr LRN for my vintage 1911, for nice easy accurate target loads. The same load in Auto Rim,for 230 gr is not even listed in the Sierra Manual, and starts at 4.9 gr. Shouldn't the loads be the same,it's the same case.

zippy13 · April 1, 2011, 08:17 PM

Sea Buck,
Out of curiosity, I checked my Lyman Cast Bullet Handbook and there are significant differences between the ACP and Auto-Rim recipes.

Perhaps you are assuming the cases are more identical than they may actually be. Have you done a capacity comparison between the ACPs and the Auto-Rims? I haven't shot any Auto-Rims since the advent of the full moon clips, so I don't have any cases on hand.

Sea Buck · April 2, 2011, 09:28 AM

Zippy, all my books show a significant difference in load data between .45 AR and ACP

. My only conclusion is that the AR round needs more gusto to get it through the forcing cone,whereas in the 1911 the bullet is in the barrel and does not need that extra power. However it does need enough to cycle the slide

.Having said that I'm going with 6.4 of Unique,4.9 of Bullseye or 6.6 of Herco, with a 230 gr Reinier FMJ to get the job done

.These will be about 850fps according to my Sierra Handgun Reloading Manual for .45 ACP. Listed as 700fps in the Auto Rim section!

Rich/WIS · April 3, 2011, 01:54 PM

Major difference in auto VS revolver. Auto burns powder entire length of barrel, revolver pressure drops once bullet clears the cylinder due to gas loss between the barrel and cylinder. Also loads for the AR are often used in vintage revolvers like the 1917 and although designed for 45 ACP pressures I don't think the idea was that they would still be in use nearly a century later. That is why lead bullets are recommended to reduce barrel wear. It is a lot easier to find and replace a barrel in a 1911 than in a 1917.

April 1, 2011, 11:05 AM	#1
Sea Buck Senior Member Join Date: September 9, 2008 Location: New England,Florida Snow Bird Posts: 312	.45 Auto Rim:What Load ? Looking in my Sierra Handgun Loading Manual I see a loads on the low end of the velocity scale that when compared to .45ACP in the same manual these loads are in the Max velocity area. For instance 6.4 gr of Unique in Auto rim for a 230 gr FMJ is listed as 700fps, the same load in .45 ACP gives 850 fps. For Bullseye in AR it's 4.9 gr / 750fps, and in ACP 4.9gr it's 850 fps. I don't understand this.Why does the same load in ACP give a higher velocity,it's the same case. I really don't want to shoot my 93 year old S&W at service load pressures. What do I use?

April 2, 2011, 09:28 AM	#5
Sea Buck Senior Member Join Date: September 9, 2008 Location: New England,Florida Snow Bird Posts: 312	Zippy, all my books show a significant difference in load data between .45 AR and ACP. My only conclusion is that the AR round needs more gusto to get it through the forcing cone,whereas in the 1911 the bullet is in the barrel and does not need that extra power. However it does need enough to cycle the slide.Having said that I'm going with 6.4 of Unique,4.9 of Bullseye or 6.6 of Herco, with a 230 gr Reinier FMJ to get the job done.These will be about 850fps according to my Sierra Handgun Reloading Manual for .45 ACP. Listed as 700fps in the Auto Rim section!

April 1, 2011, 11:23 AM	#2
zippy13 Senior Member Join Date: August 23, 2008 Location: SoCal Posts: 6,442	Are the test guns/barrels the same? One thinks of .45 ACPs being used in 1911s and .45 Auto Rims in revolvers. I shoot 3.5 gr Bullseye under a 200-gr LSWC in my 1917.

April 1, 2011, 01:05 PM	#3
Sea Buck Senior Member Join Date: September 9, 2008 Location: New England,Florida Snow Bird Posts: 312	Zippy, I use 4.5 gr Bullseye under 230 gr FMJand 4.0 Bullseye under a 230gr LRN for my vintage 1911, for nice easy accurate target loads. The same load in Auto Rim,for 230 gr is not even listed in the Sierra Manual, and starts at 4.9 gr. Shouldn't the loads be the same,it's the same case.

April 1, 2011, 08:17 PM	#4
zippy13 Senior Member Join Date: August 23, 2008 Location: SoCal Posts: 6,442	Sea Buck, Out of curiosity, I checked my Lyman Cast Bullet Handbook and there are significant differences between the ACP and Auto-Rim recipes. Perhaps you are assuming the cases are more identical than they may actually be. Have you done a capacity comparison between the ACPs and the Auto-Rims? I haven't shot any Auto-Rims since the advent of the full moon clips, so I don't have any cases on hand.

April 3, 2011, 01:54 PM	#6
Rich/WIS Junior Member Join Date: January 12, 2009 Posts: 5	Major difference in auto VS revolver. Auto burns powder entire length of barrel, revolver pressure drops once bullet clears the cylinder due to gas loss between the barrel and cylinder. Also loads for the AR are often used in vintage revolvers like the 1917 and although designed for 45 ACP pressures I don't think the idea was that they would still be in use nearly a century later. That is why lead bullets are recommended to reduce barrel wear. It is a lot easier to find and replace a barrel in a 1911 than in a 1917.